1. Field of the Invention
The present invention relates to a connecting apparatus for an electronic device, and more particularly, to a socket for mounting memory module boards on a printed circuit board (PCB).
2. Description of the Related Art
With the advance of technology, multi-media computer systems, servers, and workstations have experienced increasing needs for high-capacity, highly integrated and high-performance electronic devices. Memory modules particularly need to be small and fast devices. In many applications, the sockets that connect memory module boards to a PCB, are important factors in determining the performance of a computer system.
FIG. 1 is a cross-sectional view of a socket for mounting a memory module board on a general PCB. In FIG. 1, the socket is on a PCB 61 having a single-layer or multi-layer printed circuit pattern (not shown). The socket includes a socket body 51, upper socket pins 55, lower socket pins 57 and socket mounting posts 59. The socket mounting posts 59 can be soldered onto the PCB 61 to fix the socket on the PCB 61. In FIG. 1, a signal line 63 connects the upper and lower socket pins 55 and 57 to the printed circuit pattern of the PCB 61.
FIG. 2 is a perspective view illustrating a signal transmission system including sockets 65 for mounting memory module boards on a general PCB 61. In FIG. 2, when a unit memory module board 53 is inserted in a socket 65, input or output terminals of the memory module board 53 are connected to the signal lines of the PCB 61 (e.g., A of FIG. 2) through the socket 65. The signals transmitted to the PCB 61 are again transmitted to another memory module board 53 mounted in a neighboring socket 65. In FIG. 2, dotted lines indicate paths along which a signal line 63 within a socket 65 is connected to a neighboring socket 65 through the PCB 61.
In the case of a memory module board operating at a high frequency, impedance matching between the PCB 61, which is a main board, and the memory module board 53 is very important. If the impedances are improperly matched, phase inversion of signals may occur at the interface between the PCB 61 and the memory module board 53. This causes distortion of transmitted signals. Accordingly, a desired signal cannot be obtained or a signal arrival may be delayed. This effect becomes severe for faster and smaller memory modules.
Another problem with the conventional sockets of FIGS. 1 and 2 is that each socket can only accommodate a single memory module board, and each socket requires sufficient area for insertion of a memory module board. Accordingly, the memory module mounting area cannot be easily reduced, which is difficulty for miniaturized electronic systems.
To solve the above problems, an embodiment of the present invention provides a socket for mounting memory module boards on a printed circuit board. The socket can accommodate multiple memory module boards, reduce the area required for the memory module boards on the PCB, can suppress distortion of signals at the interface between memory module boards by directly conducting signals therebetween, and can speed up the process of fetching data.
One embodiment of the present invention is a socket for mounting memory module boards on a printed circuit board (PCB). The socket includes a socket body that accommodates at least two memory module boards, at least two sets of upper socket pins, and at least two sets of lower socket pins. The memory module boards are inserted and fixed between the upper socket pins and the lower socket pins. A signal line connects to the upper and lower socket pins within the socket body and extends outside of the socket body. In an exemplary embodiment, the socket body is formed of an insulator in an xe2x80x9cIxe2x80x9d shape, so as to be capable of mounting the memory module boards opposite sides, and further includes at least one socket mounting post for fixing on the PCB. The memory module boards inserted into the xe2x80x9cIxe2x80x9d shape socket body are parallel to the PCB.
Also, the upper socket pins may include a first upper socket pin for connecting the first memory module board, and a second upper socket pin for connecting second memory module board. Further, the lower socket pins may include a first lower socket pin for connecting the first memory module board, and a second lower socket pin for connecting second memory module board.
The signal line often connects to a signal line formed in or on the PCB.
Also, in the exemplary embodiment, socket pins in each set of upper or lower socket pins may connect within the socket body, to respective socket pins in another set of upper or lower socket pins. Alternatively, the two or more sets of upper socket pins are not connected to each other but are connected to the PCB. Similarly, socket pins in the two or more sets of lower socket pins can be electrically isolated from each other within the socket body and independently connected to the PCB.
According to another aspect of the present invention, a socket for mounting memory module boards on a printed circuit board (PCB) includes a first socket, a second socket and a third socket. The first socket includes a first socket body that receives a first memory module board, a first clip that connects to a tab of the first memory module board, and a first signal line connected to the first clip and extending outside of the first socket body. The second socket is in an area adjacent to the first socket and includes a second socket body that receives the first and a second memory module boards on opposite sides of the second socket body, two sets of upper socket pins disposed within the second socket body, and two sets of lower socket pins disposed to be opposite to the upper socket pins. The third socket is in an area adjacent to the second socket and includes a third socket body that receives the second memory module board, a second clip that connects to a tab of the second memory module board, and a second signal line connected to the second clip and extending outside of the third socket body.
Preferably, each of the first, second and third socket bodies further includes a socket mounting post, and the second socket body is separable into upper and lower parts thereby separating the upper and lower socket pins. Also, the second socket body preferably further includes a connector that attaches the upper part to the lower part.
In a preferred embodiment of the present invention, the memory module boards have tabs on the left and right sides thereof.
Also, the first clip, the upper and lower socket pins and the second clip are preferably configured such that signals from the tabs of the first and second memory module boards are serially connected without passing through the PCB, and the first and second signal lines are preferably connected to interconnections of the PCB to which the first and second sockets are fixed.
Also, the socket according to the present invention may further include at least one more socket having the same configuration as the second socket, between the first socket and the second socket. Here, at least one or more first clip, intermediate connection part of upper and lower socket pins and second clip may be additionally provided stacked vertically above or below one another within the first, second and third socket bodies.
Also, the memory module boards inserted into the first clip, the upper and lower socket pins and the second clip which are additionally provided in the first, second and third socket bodies, preferably have tabs on the left and right sides thereof.
The first clip, the upper and lower socket pins and the second clip which are additionally provided in the first, second and third socket bodies, are preferably configured such that signals from tabs of the memory module boards are serially connected without passing through the PCB. Alternatively, the first clip, the upper and lower socket pins and the second clip which are additionally provided in the first, second and third socket bodies, are configured such that they are not connected to another first clip, another sets of upper and lower socket pins and another second clip, respectively, within the first, second and third socket bodies.
According to the present invention, a socket for a board of a fast and miniaturized memory module enables the size of a PCB to be reduced by reducing the mounting area of the memory module board, thereby attaining miniaturization and integration of electronic systems. Also, signal distortion occurring at the interface between the PCB and the memory module board can be suppressed, thereby avoiding signal distortion and improving the fetching speed of data.